In an information recording medium, such as, for example, a CD-ROM (Compact Disc-Read Only Memory), a CD-R (Compact Disc-Recordable), and a DVD-ROM, as described in patent documents 1 and 2 or the like, there is also developed an information recording medium, such as a multilayer type, double layer, or multiple layer type optical disc, in which a plurality of recording layers are laminated on the same substrate. More specifically, a dual layer type optical disc has, as a first layer, a first recording layer located on the front (i.e. on the closer side to an optical pickup) as viewed from the irradiation side of laser light at the time of recording by an information recording apparatus, and it further has a semi-transmissive reflective film located on the rear side thereof (i.e. on the farther side from the optical pickup). Moreover, the dual layer type optical disc has, as a second layer, a second recording layer located on the rear side of the semi-transmissive reflective film through an intermediate layer, such as an adhesive layer, and it further has a reflective film on the rear side thereof. Then, on an information recording apparatus, such as a CD recorder, for performing the recording with respect to the dual layer type optical disc, laser light for recording is focused on the first recording layer, to thereby record information into the first recording layer in an irreversible change recording method by heat or a rewritable method. Moreover, the laser light is focused on the second recording layer, to thereby record information into the second recording layer in the irreversible change recording method by heat or the rewritable method.
In particular, as disclosed in a patent document 3 or the like, there is proposed a method of inserting an intermediate layer with so-called wavelength selectivity (hereinafter referred to as a “wavelength-selective layer”, as occasion demands) between two layers of the dual-layer type optical disc provided with the recording layers in each of which the recording can be performed by irradiating laser light with two different wavelengths onto one signal surface, wherein the wavelength selectivity means that a reflectance with respect to the laser light with one relatively short wavelength is relatively high and a reflectance with respect to the laser light with the other relatively high wavelength is relatively low. Therefore, both a reproducing apparatus which emits the laser light with the one wavelength and a reproducing apparatus which emits the laser light with the other wavelength can perform reproduction on the recording medium, so that it is possible to maintain reproduction compatibility.
Moreover, as disclosed in a non-patent document 1 or the like, there is also invented a recording medium, such as a dual-layer type optical disc, provided with: (i) one recording layer in which the recording can be performed by using laser light with one wavelength, irradiated on one signal surface of the optical disc; and (ii) another recording layer in which the recording can be performed by using laser light with another wavelength, irradiated on another signal surface of the optical disc.
On the other hand, as disclosed in a patent document 6 or the like, there is also invented an optical disc which can display a so-called pit art, which is a display pattern that can be visually recognized, such as an image and a character or text, by forming a dummy pit along a spiral track on a label surface, for example.    Patent document 1: Japanese Patent Application Laid Open NO. 2000-311346    Patent document 2: Japanese Patent Application Laid Open NO. 2001-23237    Patent document 3: Japanese Patent Application Laid Open NO. Hei 9-237438    Patent document 4: Japanese Patent Application Laid Open NO. 2004-95092    Patent document 5: Japanese Patent Application Laid Open NO. 2003-91868    Patent document 6: Japanese Patent Application Laid Open NO. Hei 10-283676    Non-Patent document 1: [online] “Enter the Blu-Ray Disc and CD Integrated Disc”, the Internet <URL:http://nikkeibp.jp/wcs/leaf/CID/onair/jp/elec/337888>